This invention relates to an automatic trim controller for a marine propulsion unit and more particularly to an improved trim controller that will provide the proper trim control for all conditions.
In substantially all marine propulsion systems, the optimum trim angle of the propelling unit relative to the hull of the watercraft varies with a number of conditions. As a general rule, when the watercraft is being accelerated from standstill, the optimum trim angle is a trim down angle wherein the propulsion unit has a maximum degree of submersion. However, as the watercraft reaches crusing speeds, the optimum trim angle is substantially less. In addition to speed, such factors as the weight in the watercraft and a variety of other conditions affect the optimum trim angle. It has been proposed to provide devices which permit the operator of the watercraft to adjust the trim angle of the propulsion unit during running of the watercraft. In addition, automatic trim sensing devices have been proposed wherein the trim angle of the propulsion unit will be varied to suit running conditions. However, those systems which have been proposed for automatic control generally are programmed to operate in response to only one predetermined condition, normally either watercraft or engine speed and, hence, are not truly sensitive to all conditions so as to set the optimum trim angle.
It is, therefore, a principal object of this invention to provide an arrangement for automatically trimming a marine propulsion unit that is responsive to all conditions.
It is a further object of this invention to provide a method for trimming an outboard motor that will provide the optimum trim angle under all running conditions.